The body of evidence about nuts and health continues to grow. These local and international research papers, published around June 2022, corroborate decades of research about the importance of a regular handful of nuts in a healthy diet.

Nuts and legumes consumption and risk of colorectal cancer: A systematic review and meta-analysis. (2022).
This meta-analysis of observational studies looked into the association between the consumption of nuts (13 studies) and legumes (29 studies) and the risk of colorectal cancer. Those who consumed the most nuts and legumes had a 16% and 10% lower risk of colorectal cancer, respectively – compared with the lowest consumption. Based on the dose–response analysis, a 28g/day increment of nut consumption was linked with a 33% lower risk of colorectal cancer. While promising, the researchers say further well-designed studies are needed in this area.

The effect of pistachio supplementation on metabolic syndrome and its components in adults: A systematic review and meta-analysis of randomized controlled trials. (2022).
This systematic review and meta-analysis of 17 randomised controlled trial, involving 940 adults, found that pistachio consumption could improve some components of metabolic syndrome. Pistachio supplementation significantly reduced systolic blood pressure (mean difference (MD): –2.89mmHg), triglycerides (MD: –16.76mg/dL), fasting blood glucose (MD: –3.62mg/dL) and increased HDL (MD: 1.43mg/dL) levels, without affecting anthropometric indices (waist circumference and body mass index), and diastolic BP.

The effect of walnut supplementation on dietary polyphenol intake in the Walnuts and Healthy Aging Study (WAHA). (2022).
In this two-year prospective, randomized intervention trial, dietary polyphenol intake of participants who added walnuts daily to their diets, at 15% of daily energy, were compared to those in a control group with a walnut-free habitual diet. The walnut group had a higher intake of dietary total polyphenol, total flavonoids, flavanols and phenolic acids, compared to the control group. Nuts and seeds were also found to be the third highest contributing source of total polyphenols in the diets of study participants, suggesting that adding a single food, like walnuts, to the daily diet can increase polyphenol intake in a population.

The impact of daily walnuts consumption and lifestyle changes on dyslipidemia. (2022).
This research involved 120 adults, aged 30-60 years, with a high lipid profile. They were divided into control (n=60) and experimental (n=60) groups, with both following a low-calorie diet and exercising, but the latter also assigned 30g walnuts daily. After 90 days, the walnut group had a significant reduction in body weight (-5.4%) and BMI (-4.0%), compared to the control group (-1.9% and -2.1%, respectively). Other markers, including total cholesterol, LDL-cholesterol and triglycerides were all significantly lower in the experimental group, but non-significant in the control group.

Mixed nuts as healthy snack: Effect on gut microbiota and tryptophan metabolism. (2022).
This randomised controlled trial involved 95 overweight people. Compared to baseline, kynurenine (a tryptophan metabolite) levels were significantly reduced in the group who consumed 42g nuts/day at the end of a 12-week weight loss phase and returned to baseline concentration after 12-weeks of an isocaloric weight maintenance program. The researchers suggest nut consumption may directly affect tryptophan-kynurenine metabolism, with potential benefits to heart rate and BMI in overweight people.

Omega-3 index is associated with cardiometabolic risk factors but is not improved by walnut intake in free living elderly: A single blind, randomized controlled trial. (2022).
This research looked at whether regular intake of α-linolenic acid (ALA) raises omega-3 index in older adults. Participants were assigned to either a walnut (15% of daily energy from walnuts) or a control group (usual walnut-free diet). Red blood cell fatty acids were determined at baseline and 1-year following intervention. The researchers found consuming ALA-rich walnuts did not raise the omega-3 index in elders. However, they say that incorporating walnuts as part of heart healthy diets should still be encouraged.

Synergistic interactions between tocol and phenolic extracts from different tree nut species against human cancer cell lines. (2022).
Tree nuts are unique because they contain an oily fraction and a polar fraction, so have both lipophilic and hydrophilic bioactive compounds. In this study, the activity of tocol-rich extracts (oily fraction) and phenolic-rich extracts (polar fraction) from tree nuts and the extracts combinations, were evaluated in four cancer, and one control, cell lines. It found the combination of both extracts had greater effectiveness, showing strongly synergistic interactions. The researchers say their finding highlight the importance of the interactions among the multiple bioactive compounds in foods and food matrixes, in understanding their health-promoting potential.